Blood Test Might Spot Cancer Years Earlier

THURSDAY, July 23, 2020 (HealthDay News) — Scientists are working on a blood test that may catch five common cancers years sooner than current methods.

The blood test, which is still experimental, hunts for certain genetic “signatures” associated with tumors. Researchers found that it can detect five types of cancer — colon, esophageal, liver, lung and stomach — up to four years earlier, compared to routine medical care.

More research is needed to confirm the test’s accuracy. But these initial results “offer hope,” said researcher Kun Zhang, a professor of bioengineering at the University of California, San Diego.

Having a “convenient and quick” blood test that can catch cancers earlier could give people more treatment options, and hopefully improve their survival odds, Zhang said.

In fact, such a test is the proverbial “holy grail” in cancer research, said Dr. William Cance, chief medical and scientific officer of the American Cancer Society.

A number of experimental blood tests have been studied and are under development. But the new study, Cance said, is an “important step forward.”

“This test has one of the highest sensitivity rates that’s been reported, and it’s able to do it with a relatively small blood sample,” he said.

Sensitivity refers to a test’s ability to accurately pick up all people with a disease. In this study, the blood test had a sensitivity rate of about 95% in people free of cancer symptoms.

However, both Zhang and Cance stressed that there’s a long road ahead.

As a next step, the test performance should be validated in additional study groups, according to Cance.

And ultimately, Zhang said, any blood test for cancer screening would have to be proven in a clinical trial.

The concept of using a blood test to detect early-stage cancers is based on a simple fact: Tumor cells regularly shed bits of their DNA into a person’s bloodstream.

A snag, however, is that the DNA is present in only small amounts — especially when tumors are small. That can make it hard to pick up, according to Zhang.